Protect against accidental namespace deletion

[JohnStrunk]

Describe the feature you'd like to have.
The lifetime of the snapshot should be independent of the namespace of the PVC.

What is the value to the end user? (why is it a priority?)
Snapshots that reside in the same namespace as the primary data don't protect against accidental namespace deletion.

How will we know we have a good solution? (acceptance criteria)

• If a namespace containing the primary data is deleted, the scheduled snapshots should survive.
• All the other scheduling features should continue to work as intended (e.g., expiring old snaps)

Additional context

• There seem to be (at least) two approaches:
  • Transfer the VolumeSnapshot object (by re-binding the VSC) to a different namespace
  • Change the deletion policy of the snapshot content such that it is retained even if the VS is deleted
• The work on volume namespace transfer may be useful here KEP Proposal: API for PVC Namespace Transfer kubernetes/enhancements#1555

[KyriosGN0]

Hey, i ran into this issue a few days back, so a solution like that in snapscheduler would be great!